You can't believe everything you see, but you can certainly read into it a lot and make a ton of assumptions about what a certain Instagram may mean. (Which is exactly what we're about to do.)
As pointed out by Vogue, both the model-turned-actress and singer-queen-of-the-world posted identical photos of a mixing board. (And their hands were on the mixing board, and unless it's the greatest coincidence in the history of time and space, this means they were at least at the same studio at the same time.)
But that is literally all we know: that, a) they've just completed the greatest publicity stunt, or b) this is a musical collaboration that frankly, I'm interested in. Again, as pointed out by Vogue, Delevingne is actually a pretty proficient drummer, so it's not like she's just a random person waltzing in without a first-hand knowledge of what music is.
They're also pals: the two have been photographed together before, and run in the same circles, so at least a day hanging out in a professional space makes sense. (Stars: they're not just like us — they can hang out in studios if they want to.) Plus, the lack of caption on the photos imply they're trying to send a message.
Or, more specifically: each are social media experts and know exactly what's going to launch a million articles. Either way: would you be down with a collab or would it all be too much?